The present application relates to an earthmoving system, for example a bulldozer, for contouring a tract of land to a desired finish shape and, more particularly, to a system in which the position of the cutting tool is controlled based on information from GPS receivers and cutting tool position sensors, such as gyroscopic sensors and accelerometers.
Various control arrangements have been developed to control earthmoving devices, such as bulldozers, so that a tract of land can be graded to a desired level or contour, for example, known as a terrain contour design. A number of systems have been developed in which the position of the earthmoving apparatus is determined with GPS receivers. In such systems, a site plan is developed with the desired terrain contour design. The terrain contour design may be a representation of the topology of the tract of land as designed. The terrain contour design and the tract survey may be stored in the computer control system on the bulldozer. From the terrain contour design and the tract survey, amounts of cut or fill needed in specific areas of the tract to produce the desired terrain contour design may be determined.
The earthmoving apparatus determines the position of the cutting tool of the bulldozer using the GPS receivers and/or other sensors mounted on the bulldozer body or on masts attached to the blade of the bulldozer. The earthmoving apparatus determines the position of the cutting tool based also on the position sensors located on various mechanical control devices of the earthmoving apparatus. A computer control system calculates the blade position for the blade based on the terrain contour design and the tract survey and on the detected position of the blade. The blade position or a blade position error may be displayed for the operator of the bulldozer who can then make the appropriate adjustments manually. Alternatively, the computer may automatically control the position of the blade to reduce blade position error.